Indicating system



l "July l5 1947- E. B. r-'EFmrsLL'v 2,423,829

. INDlcA'rING SYSTEM Filed Sept. 16, 1943 2 Sheets-Sheet 1 VULUHE C july`5, l947- E. SB. FERRELL 2,423,829

' INDIcATme SYSTEM Filed sept. 16, 1943 2 sheets-sheet 2 Has 5F16. 4

VE N TOR B YE a FERRELL Arronsr A Patented July 15, 1947 lNnlcA'rlNG SYSTEM Enoch B. Ferrell, Chatham, N. J., assignor to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of `New York Application September 16, 1953, Serial No.502,627

4 claims. (ci. 315-214) I This invention relates to the determination of the range, azimuth and elevation of a fixed or moving object, and more particularly to arrangements in which electromagnetic waves are transmitted from an observing station'to the object, the time of travel of the waves to the object and return being observed together with the direction of propagation of the returned wave' as indicated by a direction nding device.

An object of the invention is to facilitate rapid and continuous determination by a single unaided observer of the range, azimuth and elevation of an object while the object and the observer may be moving relatively to each other at a rapid rate.

A related object is to simplify the necessary equipment and procedure to a point which will enable the observer to make substantially simultaneous observations of the three above-mentioned coordinates ofthe object under observation. y

A feature of the invention is the use of a single A'display device such as an oscilloscope to indicate Range measuring equipment I2 is provided having a range scale 'I3 and the receiving equipment I I is provided with an azimuth dial I4 and an elevation dial I5. The setting of the range measuring device I2 and the accompanying reading of the scale I3 may be adjusted by means of a knob 6. The azimuth and elevation anglesA of thereceiving device II and the accompanying readings of scales associated with the dials -I4 and I5 may be controlled through suitable means, such as gearing, which may be provided with handles I 6 and I 'I respectively. Electrical responses from the range measuring device I2 and the directional receiving equipment I I are transmitted through motor driven commutating means indicated generally at I8 to the deection plates of a cathode ray osclllosope I9."

During operation of the system 'of Fig. 1, a distinctive pattern or trace appears upon the ,screen 2| of the oscilloscope I9 to guide the operator to the correct settings of the scale I3 'and hereinafter.

The range measuring device I2 is preferably of the general type disclosed and claimed in the copending applications of E. Bruce, Serial No.

indicated on separate scales or dials whenever the oscilloscope shows that the deviations have been rendered substantially nil.

In the drawings:

Fig. 1 is a schematic representation of a measuring and indicatingsystem in accordance with4 the invention;

Fig.' 2 is a diagram useful in explaining the electrical commutations employed in the system of Fig. 1;

Fig. 3 is representative of the pattern which may appear upon the screen of the oscilloscope when the correct values of the range, azimuth and elevation have not been determined; and

Fig. 4 is representative ofthe pattern appearing when the correct readings of these quantities are being exhibited on the respective scales or dials in the arrangement of Fig. 1.

In the arrangement of Fig. 1 there are pro-- vided atransmitting antenna I0 for sending out electromagnetic Waves, preferably of ultra-short or quasi-optical wavelengths, and a directionally selective receiving system II-for such waves, capable of being pointed in any desired direction.

499,211, filed August 19, 1943, and of G. Hecht, Serial No. 592,619, filed September 16, 1943, and assigned to the assignee of the present application. The Bruce and Hecht systems are of the general typein which an electro-magnetic wave is transmitted from the observing station to the object, the range of which is, to be measured, and

an echo wave returning from the object is em- 4 ployed to make a distinguishing mark in the pattern of an oscilloscope, the cathode ray of which.

is meanwhile caused to sweep across the screen at a substantially constant time rate. systems, the oscilloscope screen is provided with a xed index mark, preferably at the center of the screen. The starting point of the cathode ray in its sweep across the screen is made aci justable under the control of means coupled to the movable member of the range indicator so that the time required for the cathode ray to reach the xed index mark may be varied. When the correct adjustment has been made, the cath- In these' 3 on the oscilloscope pattern by the echo wave is coincident with the index niark. He may then read the correct range from the range scale. It will appear that in arrangements in accordance with the present invention, lthe ilxed mark may be dispensed with.

Reference may be made to the cited applications oi Bruce and Hecht for a detailed description of the range measuring device. According- 1y. only such details as will facilitate the description oi' the present invention are repeated herein. The range measuring device includes a pulsing circuit 22, the function of which is to control the emission of the transmitted pulse and the simultaneous start'o! the cathode ray sweep. To control the transmitted pulse, the pulsing circuit is connected to an oscillator 23 of suitable high frequency which is in turn connected to the transmitting antenna I0. As directivity is not essential in the transmitter, the antenna I8 may be a simple dipole. To control the cathode ray sweep mechanism, the pulsing circuit 22 is connected to a start-stop circuit 24,

The timingof the sweep is under the control oi a circuit of preferably substantially fixed resistance and xed capacity comprising a resistor 25, a potentiometer 28 and a condenser 21, the elements 25, 26 and 21 being serially connected across the terminals of a source 28 of substantially constant electromotive force. A space discharge device 29 having a cathode til, a grid 3| and an anode t2 is connected with its cathodeanode circuit in parallel with the condenser 21 to substantially short-circuit the condenser when the cathode-anode circuit is made conductive under the control of the grid 8i. The start-stop circuit, which is disclosed in detail in the above-cited Bruce application, controls a re sistor 33 which is connected between the grid El and the cathode 39. Immediately prior to the operation of the pulsing circuit 22 to send out a pulse from the antenna it, the resistor 33 is carrying abiasing current supplied by the start-stop circuitd to render the grid @i positive and thereby hold the tube 2t in the conductivestate. Accordingly, there is substantially no potential difference between the plates`of the condenser 21 and the various points along the potentiometer 26 are at graduated potentials clue to the ow of vcurrent fromr the source 23 through the tube 29. The potential at the point of contact attached to the mob t on the movable arm of the potentiometer 2t depends upon the position of the movable arm. This potential is impressed upon a deection amplifier 3d by means of a lead 35. The cathode side of the condenser 21 is connected to the opposite terminal of the deflection amplier 34 through a. lead 36. .at the instant of sending out the transmitted pulse, the start-stop circuit 2t reverses the biasing current through the resistor 33, rendering the tube 29 non-conductive. Immediately the current from A the source 28 is diverted to charge the condenser 21 and accordingly thereafter all points along the potentiometer begin an exponential rise in potential, the early part of which rise in substantially linear, as is well known. The rising potential oi the movable point of the potentiometer, andhence the lead 35 acts through .the deection amplifier 34 to sweepthe cathode ray across the screen o! the oscilloscope. After a suilicient time interval to accommodate the return wave from the most distant point to be measured, the startstop circuit 24 again reverses the polarizing current in the resistor 33 and renders the tube 2.3

4 conductive. 'I'he condenser 21 discharges rapidly through the tube 28 thereby -restoring the system to the condltionfdescribed as holding before the transmitted pulse was emitted. Upon the restoration of the timing circuit, the pulsing circuit acts to'initiate another transmitted pulse and the process may be repeated at a rapid rate.

The receiving device I I may comprise a pair of double lobe directive receiving arrays 31 and 38, each of which may be of any suitable typev as for example the structure disclosed in United States Patent 2,002,181, issued May 21, 1935, to W. Ilberg. Instead of connecting the array to a transmitter as in the patent, the array is connected to a receiver. The array 31 is arranged with its axis vertical and `is directionally selective with respect to the azimuth of a received wave.A The array 38 is arranged with its axis horizontal and is 'directionally selective as to elevation. The array 31 comprises dipole antenna pairs 43, 44 and 41, 48V, mounted parallel to but somewhat displaced from the focal line of a parabolic cylindrical reflector 39. The array 38 comprises dipole pairs 4I, 42 and 45, 48 similarly disposed with respect to a reflector 40. The assembled array 31 is suitably attached to the azimuth dial i4 which has a graduated scale of angles at its periphery and may be driven by gearing 5I attached to the handle I6. The scale of the dial I4 may be read with reference to a fixed pointer 52. The assembled array 38 is suitably attached to the elevation dial I, also graduated. and driven by gearing 53 attached to the handle I1. rif'he scale oi the dial I5 may be read against a xed pointer 54.

The commutating system I8 comprises two commutators 55 and 58 rotatable synchronously by means of a motor 51. The commutator til comprises a central conductive portion 88 which is integral with a conductive quadrant 8l to which contact is continually made during revolution by means of a brush 52. About the periphery of the commutator 55 are symmetrically arranged four contactors 1I, 13, 15 and 1l which are connected respectively to the receiving dipole elements 4I, 43, 45 and 41. The remaining receiving dipole elements 42, 44, 48 and 48 are connected to ground at 80. The brush 82 connects through a lead BI to a radio receiver @2.

The commutator 56 comprises four conductive segments insulated from each other and connected to individual slip rings Hill. symmetrically arranged around the periphery of the commutator 56 are four contactors ti, Q2, 93 and tit. The contactors 92 and 94 are connected to the respective output terminals of the deflection ampliiier 34 and the contactors SI and 93 are connected to the output terminals of the radio receiver 82. A source 95 of biasing potential is connected in series with the contactor 9|.

Fig. 2 illustrates the commutating scheme in a simplied form. The curves I'lI and H5 represent the response characteristics or lobes for the receiving dipoles 4I, 42 and 45, 48 respectively, corresponding to the lobes I and 3 of Fig. 1 of the Ilberg patent. 'I'he lobes H3 and I|1 are for the dipole pairs 43, 44 and 41, 48 respectively. The lobes H3 and I|1 are represented on the top surface of an imaginary cube with the lobes Ill and H5 on a vertical face of the cube in order to indicate that the lobes II3 and II1 pertain to the azimuth and the lobes III, IIS to the elevation. In the commutating position shown in Fig. 2, which corresponds in this respect with Fig. l, the lobe Ill is represented as being conv nected in circuit through a conventionalized connection -|2l. At the same time the pulsing terminals 9| and- 99 are shown connected to the upper and lower plates 0I and 98 respectively,

while the sweep circuit terminals 92 and 94 are connected to the plates 91 and 99 respectively.

The function of the commutating arrangement is to connect the four receiving dipoles in rotation to the radio receiver and at the same time to vary the connections from the deection ampliiier and from the radio receiver to the deflecting plates of the oscilloscope in a proper cyclic manner to produce a distinctive pattern on the screen 2| by which the operator may be guided in properly setting the various dials. The plate 98 when positively charged with respect to the plate 88 acts to deilect the cathode ray upward in the diagram of Fig. 1. The plate 91 when positively charged with respect to the plate 99 deilects ythe cathode rayto the right. Similarly, the plate 98 when positively charged with respect to the plate 98 produces a downward deection and plate 98 when positively charged with respect to plate 91 vdeilects the cathode ray to the left. With the commutators in the position shown in Figs. 1 and 2, the receiving dipole 0|, 42 has its element 0I connected through the contactor 1I, brush 82 and lead 8| to the ungrounded side of the radio receiver 82. At the same time the biasing source Slihas its positive terminal connected through the contactor 9| to the deilecting plate 98,thereby causing the cathode ray to trace a horizontal line |0| near the top of the screen 2| in the oscilloscope I9, as shown in Fig. 1. While the commutators are in the position shown, a plu'- rality of pulses are sent out from the transmitting antenna i0 and received on the 4receiving dipole 0I, 02. As long as the .range ofithe object is not changing too rapidly, the receiving lpulses will make a mark such as |02 which ma be directed downward by proper adjustment of the radio receiver 82A so that the output of the radio receiver will oppose the potential of the source 95, it being assumed that the radio receiver develops a rectified or unidirectional output potential. If the range scale I9 were reading the proper range of the object under observation, the mark |02 would appear at the center of the trace |0| but in general the rst adjustment is not correct and the mark |02 is displaced to. one side or the other. The opposing potential from the radio receiver 02 acts through the contactor 93 upon the lower plate 98. The sweep potentials from the output of the deflection amplier 30 are impressed by way of the contactors 02 and 94 upon the deection plates 91 and 09 respectively, to produce the horizontal sweep from the left to right along the line |0I. The starting point of the sweep being dependent upon the setting of the range dial, the line |0| may not be complete.

Assume Vnow that the range remains substanl tially unchanged and the commutators are advanced a quarter of a revolution in the direction of revolution indicated by the arrow on the motor. The input of the radio receiver 82 is then connected to the receiving dipole element 43 through the contacter 13. At the same time the biasing source 05 is transferred to the plate 91, the other terminal of the receiver outputbeing connected to the plate 99. The deection amplifier is then connected between plates 98 and 99 to produce a downward sweep along the line I 03. The mark of the echo pulse will now appear at |04, in the 'same position with respect to the center of the sweep |09 as the mark |02 occupies with respect to the center oi' the sweep 10|, but the length oi the mark |04 will depend upon the intensity of the wave receivedby the dipole pair I8, Il. In the vcase illustrated the mark |00 is longer than the mark |02, indicating a stronger pulse from the dipole 48, Il than was received from the dipole 4|, 4 2. In general, the mark |04 in length from the mark |02.

Assuming the commutators to be advanced another quadrant, the dipole element I0 is then connected to the radio receiver 02 and the biasing sourceis connected to the plate 98. 'Il'he other commutations are' made accordingly with the result that the trace is a horizontal line |05 near the bottom of the screen and the mark ofthe echo pulse appears at |08. Provided that the will diiIer direction to the object has not changed appreciably between the making of the mark |02 and the making of the mark |08, it is evident that with the sort oi' receiver response to be expected from the structure described in the above cited patent to Ilberg, the length of the pulse |08 will be complementary to that of the pulsel02. As shown in Fig. 1, the mark |02 is longer than the mark |09 indicating that the dipole element II is receiving a greater intensity than the element 05 which is interpreted to mean that the antenna array 38 is incorrectly set and that the array should be rotated in the proper direction to equalize the intensity received at the elements 4| and 5` lIn the-example shown, a clockwise rotation oi the dial I 0 is called for, taking into account that the dipole t I 02 has its maximum sensitivity in a downward direction.v

Assuming the advance of the commutator by another quadrant, the connections will be set up so as to trace the line |01 in the upward direction, closing the ilgure, the mark |08 appearing above the center and being shown as smaller than the mark |00. VComparison of the marks |00 and |00 indicates that the dipole element 98 is receiving a greater intensity than the element 61 and consequently the dial i0 should be rotated counterclockwise to approach the correct azimuth reading.-

The speed of the motor 51 is not critical but is preferably high enough to avoid noticeable flicker in the oscilloscope pattern. A motor speed of 1800 revolutions per minute is readily available and provides for displaying the pattern thirty times per'second.

When the dials I0 and I5 have'both been rotated to the correct positions, the marks |02, |00, |06 and |08 will be of equal length. If the range scale still reads incorrectly, however, the marks will all be displaced from the center points. The displacement is in the clockwise direction in the examples illustrated in Fig. 1. A clockwise rotation loi the marks is an indication that the range scale reads too large a range. Accordingly, the range scale reading should be reduced until the marks move around to their central positions. This condition is accentuated by the factthat the marks will all point towards the center of the square. As the opposite marks will appear i`n alignment only when centered, alignment may be used to indicate the correct range reading. No index mark is then needed on the screen of the oscilloscope.

To further facilitate attaining a symmetrical I 'I'hen with a distant target the pattern would be small and as the target came closer the pattern would grow to till the screen. At this point the output volume of the radio receiver I2 could be controlled to keep the pattern a constantlsize for still closer ranges. The area of interest would always be in the very center of the screen. `Ac cordingly, in some cases, a small cathode ray tube could be used with a magnifying glass for observing the pattern. l

It it is'desirable in any instance to employ directional selectivity in the transmitting antenna as well as in the receiving antenna an 'array like l I may be used in place of the dipole Il and the lobes may be successively connected to the oscillator 23 by a commutator, like 55, which may y bedriven synchronously by the motor 51 so that when a `given lobe is in use at the transmitter,

the corresponding lobe is in use at the receiver.

Alternately, the array Il may be used for transmitting and receiving by employing known methods of duplex operation.

Fig. 3 shows a front view of the pattern 20 the same as appears in perspective in Fig. 1.

Fig, 4 .shows the appearance of the typical pattern when the range, azimuth and elevation dials have all Ibeen correctly set.

It will be evident that the procedure in reading range, azimuth and elevation" simultaneously is to adjust the dials Il, Hand I5 until the symmetrical pattern of the type shown in Fig. 4 vappears on the screen. The dial readings then vshow the correct values of range, azimuth and elevation respectively, as of the instant when the symmetrical pattern was observed.

What is claimed is:

1. A visual indicator for simultaneously selecting preferred values of three variable quantities, comprising means for displaying vfour linear marks in two parallel pairs, means to vary the relative lengths of the marks in one pair in response to changes in the valueof one of said Vvariable quantities, means to vary the relative lengths of the marks in the other pair in response to changes in the value of a second of said variable` quantities, and means to move the marks of either pair in the direction perpendicular to their lengths in response to changes in the value of the third of said variable quantities.

2. An indicating system comprising a ftime sweep circuit having a. pair of output terminals, a source of constant potential diiierence having a pair of output terminals, an oscilloscope having four deflecting plates opposed in pairs, means to connect the said Asweep circuit output terminals solely to one of said pairs of opposite deflecting plates, means to connect the said constant potential difference output terminals solely to the secon'd of said pairs o1 oppositedeflecting plates, and commutating means for periodically transferring all of said` four connections each to the next adjacent deilecting plate without changing the order of the connections, Y whereby a squareshaped pattern is formed on the lscreenfof said oscilloscope.

3. An indicating system in accordance withv REFERENCES. CITED The following references are of record in the le of this patent:

UNITED lSTATES PATENTS Number l 'Name Date 2,189,549 Hershberger Feb. 6, 1940 1,978,684 McCreary Oct; 30, 1934 2,098,695 Southwick Nov. 9,1937

V2,279,151 Wallace Apr. 7, 1942- 2,1'I2,395 McSpadden Sept. 12,1939-v 2,283,951 Ripley May 26, 1942 2,229,698

Hollmann Jan. 28, 1941 1 1A" isclamer 2,423,829`Enoe/z errell, Chatham, J. DICATING SYsT M. tent da d July 15 194 'mer led ept. 2 1949, by e assi e Bell Ze! p/one Labo tomes, I orporated. Hereby enters a1 ai cz'al Gaz Disclaimer 2,423,829.Enooh B. Ferrell, Chatham, N. J. INDICATING SYSTEM. Patent dated July 15, 1947. Disclaimer filed Sept. 20, 1949, by the assignee, Bell Telephone Laboratories, Incorporated. y Hereby enters this disclaimer to claim 1 of said patent.

[Olcial Gazette October 25, 1949.] 

